The disclosed subject matter is related to a circuit pattern inspection apparatus for detecting a gradual changing of defect expanding over a large area of the semiconductor wafer. In order to detect a gradual changing of a defect related condition expanding over a large area of the semiconductor wafer, comparison is made between dies on a wafer that are separated from each other by a distance of at least one die width. For example, when a value according to a difference between such dies exceeds a pre-determined value, an existence of the gradual changing can be confirmed.